The present invention relates to a method of manufacturing asphalt foam applicable for various types of joint filling material, and more particularly to a method of manufacturing asphalt foam with a fine foam structure and an excellent water stop function.
Some essential natures such as repellent and slow restoration are required for the joint filling material widely used in housing, vehicles, construction works, etc. One of the known joint filling materials is so-called asphalt foam having a repellent as the characteristic of asphalt and a restoring force of foam. Some of the known asphalt foams of this type are, for example, an asphalt foam in which asphalt is melted and impregnated into flexible urethane foam, and an asphalt foam in which a foam of open-cell type is impregnated with asphalt emulsion. This type asphalt foam has a good repellent due to the asphalt impregnant and a slow restoring force appropriate to the joint filling material since the restoring force peculiar to the foam is properly reduced by the asphalt. In both the above examples of asphalt foams, the foam is impregnated with asphalt. Therefore, the conventional asphalt foams inevitably suffer from nonuniform impregnation of asphalt, resulting in nonuniform quality of the products of asphalt foam. The asphalt sticked to the cell walls as the result of the impregnation is relatively easy to be taken off. Therefore, when it is repeatedly subjected to compression, the asphalt impregnant is gradually removed, leading to quality deterioration of the asphalt foam.